This invention relates to an apparatus for pressure molding ceramic articles highly efficiently to produce ceramic articles of high quality.
One of the conventional apparatuses for pressure molding of ceramic articles has been disclosed in the British Patent Specification No. 1359684.
The slip-casting apparatus according to the British Patent substantially comprises a split mold which is formed by combining two separable parts consisting of a male part and a female part, each having permeability. The split mold defines a pressure mold cavity between the male part and the female part. Liquid slip is introduced into the pressure mold cavity through a slip supply duct and after adhering to the inner walls of the male part and the female part with a sufficient thickness, non-adhered surplus slip is forced out of the pressure mold cavity through a surplus slip drain orifice which is provided separately. Ceramic articles are, thus, produced in the pressure mold cavity.
In the above construction, the split mold comprising the male part and the female part is inclined longitudinally and laterally in its entirety, allowing the surplus slip readily to flow towards the surplus slip drain orifice situated in a bottom corner position of the mold.
In order to produce a plurality of molded articles in one molding operation, the British Patent Specification has also disclosed such an arrangement that a plurality of split molds are connected in tandem and are mounted movably on a mold supporting frame.
Due to the above construction, the molded articles can be considered to be produced on a mass production basis.
However, the above apparatus for pressure molding ceramic articles still has the following problems to be solved:
(1) For collecting the surplus slip towards the surplus slip drain orifice, the split mold per se must be inclined longitudinally and laterally in its entirety, and therefore the mold supporting frame or the floor for installiling such frame must be also inclined, resulting in the apparatus having a complicated and large-sized construction which leads to the high production and installation cost.
(2) In the pressure molding apparatus which is constructed by connecting a plurality of split molds each consisting of a combination of the male part and the female part, each mold is so heavy that the separation of the male and female parts requires a considerable amount of force.
Accordingly, the manual separation imposes hard labor on workers. Although using of a hydraulic cylinder or a plurality of cylinders is considered for the separation of the male part and female part, such cylinders inevitably must withstand heavy duty and accordingly become large-sized and the mold supporting frame in which such a hydraulic cylinder is installed must be large-sized as well.
(3) In the pressure molding apparatus which is constructed by connecting a plurality of split molds each consisting of a combination of the male part and the female part, there is no connection between the surplus slip drain orifices provided on each mold, and each drain orifice independently communicates with slip deposits to be discharged through a slip drain piping, causing an intricate slip drain piping and troublesome maintenance.
(4) A slip supply passage and a surplus slip drain orifice must be provided on each split mold which is made of a combination of the male part and the female part so that the production cost of split molds becomes extremely high and the maintenance of the split mold including the opening of the clogged passage and orifice becomes cumbersome.
(5) For collecting the surplus slip towards the surplus slip drain orifice, the split mold per se must be inclined longitudinally and laterally in its entirety, and therefore it is extremely difficult to adjust the inclining angle to an angle which is most suitable for collecting of the surplus slip.
Accordingly, it is an object of this invention to provide an apparatus for pressure molding ceramic articles in which the above problems are solved, wherein, the surplus slip can be readily discharged by inclining the pressure mold cavity longitudinally and laterally without inclining the entirety of the split mold, thus enabling the pressure molding apparatus to be as compact and simple as possible.
The second object of this invention is to provide an apparatus for pressure molding ceramic articles in which the construction of the split mold can be made as compact as possible by utilizing the slip supply passage also as a surplus slip drainage, whereby the split molds can be produced inexpensively.
The third object of this invention is to provide an apparatus for pressure molding ceramic articles in which a plurality of split molds are pressed into contact with each other making the slip supply passages of all the slip molds communicate with one another, thereby facilitating the feeding of the slip to the pressure mold cavity and the discharging of the surplus slip therefrom.
The fourth object of this invention is to provide an apparatus for pressure molding ceramic articles in which a spring is interposed between each two neighboring or adjacent split molds for facilitating the separating of the split molds from each other which leads to the separation of a core mold and an outer mold. Accordingly, the removal of the molded articles can be performed easily.